Prevalence of the Trp64Arg missense mutation of the β 3-adrenergic receptor gene in Japanese subjects

Abstract

Prompted by the recent findings that a tryptophan to arginine (Trp64Arg) mutation in the β 3-adrenergic receptor gene was associated with an earlier onset of non-insulin-dependent diabetes mellitus (NIDDM) in Pima Indians, with abdominal obesity and insulin resistance in Finns, and with an increased capacity to gain weight in French whites, we studied the prevalence of this mutation in 231 diabetic and 95 nondiabetic Japanese subjects and assessed its contribution to the development of obesity and NIDDM. The allelic frequencies of the mutation were 0.18 in diabetic and 0.23 in nondiabetic subjects, showing no significant difference between the two groups ( P = .067). In nondiabetic subjects, body mass index (BMI) did not differ between those with and without the mutation (22.2 ± 3.5 v 21.4 ± 3.2 kg/m 2, P = .252). In NIDDM subjects, BMI at the time of study and maximal BMI before the start of treatment did not differ between those with and without the mutation (22.8 ± 2.6 v 23.2 ± 3.7 kg/m 2, P = .678, and 24.7 ± 2.6 v 24.9 ± 3.1 kg/m 2, P = .277). Homozygotes for the mutation did not have trends to have increased BMI in either diabetic or nondiabetic subjects. The age at diagnosis of NIDDM also did not differ between the two groups (48.8 ± 9.9 v 47.8 ± 12.5 years, P = .796). Fasting serum cholesterol and triglyceride levels and systolic and diastolic blood pressure before the start of treatment did not differ between NIDDM subjects with and without the mutation. In conclusion, although the Trp64Arg mutation is not uncommon in Japanese, it does not appear to be associated with obesity, NIDDM, age at diagnosis of NIDDM, or dyslipidemia. Our results suggest that the mutation has minor effects, if any, on the development of obesity and NIDDM in Japanese.